An Approach to Simulate Interstitial Habitat Conditions During the Incubation Phase of Gravel‐Spawning Fish

Abstract

The incubation period represents an important development phase for successful reproduction of gravel-spawning fish, whereby colmation processes can affect the quality of the interstitial habitat. From a sedimentary perspective, the infiltration and accumulation of fine sediments can result in a reduction of the pore space and limit the transport of oxygen-rich surface water in the interstitials of riverbeds. From a biogeochemical perspective, the increased surface area for microbial growth can lead to an increase of respiration rates, which additionally limits the oxygen supply. The assessment and prediction of such processes on interstitial habitat quality represents a challenging task given their complex dynamic interacting processes and their high spatio-temporal variability. This study presents a new habitat-based modelling approach, which simulates interstitial habitat suitability (IHS) to evaluate dynamically the quality of interstitial habitat conditions during incubation. For this purpose, three key parameters (hydraulic conductivity, interstitial temperature and hyporheic respiration) are linked to the habitat requirements of different developmental stages during the incubation period (egg, hatching, larvae) via a multivariate fuzzy approach. The proposed modelling concept has been developed on the River Spoel in Switzerland, whereby results of a numerical 3D sediment transport model, together with supplementary measurements, deliver the spatio-temporal variations of the required input data. The fuzzy approach provides results in form of maps and time series of IHS values to allow for an identification of abiotic bottlenecks during the incubation period. Hence, this approach represents a significant contribution for the restoration of reproduction areas of gravel-spawning fish. Figure 2. Fuzzification of the three input parameters (hydraulic conductivity, interstitial temperature, hyporheic respiration) and of the output parameter (IHS). The graphs show overlapping membership functions, which are represented by linguistic terms (very low, low, medium, high and very high) M. NOACK ET AL.

Model-Based Evaluation of the Effects of River Discharge Modulations on Physical Fish Habitat Quality

“…The absence of fine sediments, excessive biofilms, and other organic matter is crucial to the survival of the eggs and early juvenile stages. Future models should consider the sediment dynamics leading to variation in substratum quality of this habitat type [108,109].…”

From Microhabitat Ecohydraulics to an Improved Management of River Catchments: Bridging the gap Between Scales

“…flushing flows) are of major importance for aquatic biota. Noack et al () present a habitat‐based modelling approach for simulating an "interstitial habitat suitability" at the reach scale that considers dynamically varying interstitial microhabitat conditions during the egg and larval stages of gravel‐spawning fish. Although this approach requires an important effort (combinations of field measurements and three‐dimensional sediment transport modelling), it provides interesting ideas for considering hyporheic microhabitats in habitat models.…”

Controlled Reservoir Drawdown—Challenges for Sediment Management and Integrative Monitoring: An Austrian Case Study—Part A: Reach Scale

“…The direct impacts of flushing on biota can be related to various trophic levels, such as changes in algal and macrophyte communities on the lower trophic levels, which might result from human interventions via a build-up of an excessive fine sediment supply [28,29]. On a higher level, macroinvertebrates can be impacted due to smothering of the substrate and clogging of the subsurface layer, denoted as the interstitial layer [30][31][32]. Also, on a higher trophic level, fish might be affected by reduced feeding activity due to turbidity [33,34], by reduced reproduction success due to fines on spawning grounds [35], or by mechanical damage of their gills [22].…”